Central station traffic control system



J. P. TARBOX CENTRAL STATION TRAFFICl CONTROL SYSTEM I Feb. 1 2, 1935.

riginal Filed may 29, 1924 3 Sheets-Sheet 1 m.. m@ o@ o uw. Nv

INVENTOR.

Feb. 12, 1935,

J. P. TARBox 1,991,068

CENTRAL STATION TRAFFIC CONTROL SYSTEM Sheets-Sheet 2 Original Filed May 29, 1924 INI/EN TOR.

Feb. 12, 1935.

J. P. TARBX CENTRAL STATION TRAFFIC CONT-ROL SYSTEM original Filed may 29', 1924 s sheets-sheet 3 m m m m Patented Feb. 12, 193s PATENT OFFICE 1,991,068 CENTRAL STATION TRAFFIC CoNTRoI.

SYST

John P. Tarbox, Philadelphia, Pa., assigner to The Gamewell Company, Newton Upper Falls, Mass., a corporation of Massachusetts Original application May 29, 1924, Serial No. 716,804, now Patent No. 1,769,555, dated July 1, 1930. Divided and this application May 8, 1929, Serial No. 361,526. Renewed July 11, 1934 14 Claims.

My invention relates to crossing traic control systems of the order of those employed for Controlling street crossing traic in cities, towns and villages, but more particularly of the order 5 of those used for controlling the heavy traffic of large cities. t

This application is a division of my application S. N. l716,804, filed May 29, 1924, which is now United States Patent No. 1,769,555, granted July tion control and timing of signals. This control and timing will-be better understood with some understanding at least of the aims and objects of the system at large as disclosed in said applica-v An outstanding defect in most, if not all, trafc control systems is the fact that trafc from one approach or from one direction is held up during the entire period during which vtraffic is per- 20 mitted to move over the crossing from another approach or direction. Always such delays are expensive," even in the moderate traic of small towns and villages, but in the larger cities, es pecially in the largest, as in New York, the holding up of the large volumes of traflic is enormously expensive. The remedy of this defect is the central aim of my invention. Surrounding aims are the institution and preservation of an order- 1y movement of traflic over the crossing, the full 30 control of the rate of speed and volume of trafc, a secondary control over spacing and speeding of cars between crossings; the minimizing of tratlic blocks at the crossing, the placement of each crossing upon an operating basis Corresponding to its own peculiar conditions, the controlling of the relative proportions of main and cross trailic on principal highways, the establishment of full co-ordination between traiiic signals and traffic-lines, the providing for the orderly and safe crossing of pedestrians, and the placement in the hands of the trailic oicers of a positive control over every approaching and passing vehicle. There are yet many other aims of a major and minor. nature.

The central aini of theinvention is accomplished by the projecting upon the pavement from 1, 1930. Its outstanding object is the central sta- (Cl. 177-337) I onlyand to remain in them while passing over the crossing area. The tra'flcv is thus divided into ranks and les as it enters the crossing area and that order is preserved while it passes over the crossing area. The xing of the number and 5 sizes of the pockets outlined on the pavement determines the depth and spacing of the ranks and les, and the control of the speed of rotation of the turntable outlined governs both the speed and the volume of the traiiic.

The surrounding aims of the invention are accomplished through the variable projection transversely of the approaches of lines of light upon the pavement dem'ng at one and the same time the limits of approach of vehicular traffic and the paths of pedestrian trafc transversely of the crossing. Co-ordinated with the projection of these lines are open traic signals so arranged that each approach and exit of the crossing is under the individual control of the traffic oilicer. In furtherance of the method of the invention, the volume of traflic may also be varied by selectively varying the approaches from which the ranks and les are lled and by varying the character of certain of the pockets of the turntable and assignment of pockets of diierent character to diierent kinds of traiic, the relative proportion of each class of trafc may be regulated. Stated from another viewpoint, the proportions of each kind of traic are determined by apportioning the area of the crossing surface between the dilerent kinds of traic and progressively rotating the area so apportioned or assigned.- By these and other features of the method and apparatus of my invention not only 3;, the central aim but each and all of the surrounding aims are attained. Moreover, there results a number of very important incidental advantages as will be more fully appreciated after the invention is fully disclosed.

Referringto the drawings:

Figure 1 is a diagram of a time `controlling apparatus.

Figure 2 is an axial cross section of the timing switch of the apparatus per se.

Figure 3 is a perspective of certain of its contacts.

Figure 4 is a diagram of the traic signals controlled thereby.

Figure 5 is a crossing diagram of trafc under 50 control, and

Figure 6 is a perspective view of a local control box.

At the outset it should be noted that the color oi lamps 22 and 23 respectively are the same in 5 5 all four directions. The designation system used, GE, GN, GW, GS, in which the letters E, N, W and S are prefixed by the capital letter G refer, for example, to a green lamp in which the east, north, west and south directions are indicated by abbreviations for those directions. The same is true of the lamps WE, WW, WN and WS in which the prex designates a white light. Reference may be had to the issued patent above referred lto for more detailed description.

Reverting now to Fig. 4 it will be noted that the switches of the groups EW and NS not only control the traffic signals, but also control the lamps 39 which serve to project the lines or bars of light 42 across the entrances or approaches to the turntable area from each of the highways. (See also Fig. 5.) In their forward positions illustrated, each of the switches controls a part of the associated tra'ic signal of the group to which it belongs. In its rearward position each of the switches opens its traiic signal circuit and closes, or partially closes, the circuit of an associated one of the lamps 39. In technical parlance, the traic signals and the approach control signals are by these means interlocked.

Specifically speaking, switches E of groups EW and NS control over circuit 55 that one of the lamps 39 designated AE (meaning the approach on the east), switches W control over circuit 56 a similar circuit of that one of the lamps 39 designated AW, and the switches N, S, E and W of group EW control the circuit 57 of the exit control lamps EE (meaning exit east) and EW (meaning exit west) Similarly, the switches N and S of the groups EW and NS control over circuits 58 and 59 respectively the circuits vof approach control lamps AN and AS, while four switches of the group NS together control the series circuit 60 of exit control lamps EN and ES.

`The circuits 55-56--58 and 59 emanate from common conductor which in turn derives its potential from power main 154 by way of either of the emergency switches 29. Each such circuit is interlocked as between switch groups EW and NS by being subjected to a control at back contacts 161 of corresponding switches in each of the two groups so that it is closed only when corresponding switches are thrown. Each of the circuits 57 and 60 emanates also from common conductor 150 and extends n series through normal- 1y open contacts 162 of the-switches of its group only. The circuits of all the lamps 39 of the group AN, EW, etc., are connected commonly to conductor 152 through which connection is made by branch 153 to main 159.

So organized, the invention may be applied to the control of extremely heavy traffic as illustrated in Fig. 5. The positions of the switches indicated in Fig. '6 are those which will bring about the defining of traffic lines outlined in Fig. 5.` The motor control arm 25 is set to regulate the rate of movement of the turntable and resultingly the rate of speed of the vehicles on the crossing at, for example, ten and one-half (10 1/2) miles per hour. During operation pursuant to the description thus far herein presented, the presentation of a green light v'23 to the driver of a vehicle approaching the intersection along any of the highways, indicates to him that he is permittcd to enter and move over the intersection provided it is his purpose to leave the intersection by either the easterly exit EE or the westerly exit EW. Correspondingly, a white light 22 indicates to the driver of a vehicle approaching the intersection along any of the highways that he is permitted to enter and move over the intersection provided it is his purpose to leave the intersection by either the northerly exit EN or the southerly exit ES.

` In many instances it may be desirable, in order to facilitate tra'lc movement, to apportion certain sections of the turntable area solely for the use of traic having certain characteristics. VFor example, as indicated by the dotted lines of Fig. 5, two pockets have been given that special character reserving them and that portion of Ithe crossing area which they represent for east and west or Crosstown traic. It may be assumed that the dotted line bars of light are red or of some special shape, while the full line bars of light are yellow, gold, or of some other special shape indicating their character pertaining to the accommodation of north and south traflic. These relations may be changed at will by operating switch 47 or duplicates thereof controlling the special light sources 36. In the traffic condition shown in Fig. 5,it is assumed that the traic oflicer in charge of the intersection has observed the slight congestion of trailic at the westerly exit EW, and has moved the switch W of the group of switches EW to its forward position thus illuminating that part of the east and West traic signal 23 designated GW. (Three parts are extinguished).

Therefore, only tralic coming from the westerly approach enters the special pockets 61 provided for east and west trahie. 'I'he extinguishment of the signal lamps GN, GE and GS prevents any intensifying of the congestion Vobserved at the westerly exit EW and, assuming that the oicer controlling the signal lamps at the intersection has noted that such congestion extends into the turntable area and across the path of vehicles desiring to enter along the northerly approach AN, the oflicer has stopped the entry of traic from this approach by throwing oi switch N of NS. Not only has this darkened the branch WN of the north and south traido signal 22, but through the interlock circuit 58 it has illuminated the jassociated approach control lamp 39 pertaining to this approach and laid down the line of light 42, which not only bars trafc from the turntable but establishes a pathway 62 for pedestrian traflic from the pavement 63 to the illuminated island 45. Observing this pathway, pedestrians know that they are safe in crossing. The other three switches S, E and W, of the group NS are all forward, retaining closed the circuits of the corresponding parts of the north and south traic signal 22 which they control. Thus trailic from each of the other three approaches, west, south and east approaches, is apprised that the north and south line of tratic is opened'to them. No other lines 42 are laid down at this time because the remaining approaches and exits are all open forY trac. However, pedestrians noting an open pocket may cross from curb to island and the reverse by passing along with it. Indeed, if they observe that a vehicle in the pocket is not going to turn out at a given exit they may cross alongside of the vehicle. A pedestrian ymay pass beside it providing the approaching vehicles do not obstruct his pathway. Three parts of the east and west traffic controly signal 23 are dark. If now' the fourth GW be made dark, not only would there be laid down a line 42 guarding the westerly approach AW, but corresponding lines would be laid down covering the easterly and westerly exits EW and EE. k

The traflic officer can vary thesesignals and associated lines of traflic at will of Fig. 1 in which the to suit the varying trailic conditions. Should he desire east and west traic alone, the four ngers of one hand can be used simultaneously to throw all of the switches of group NS off. Or, he may use the associated operating knob 54 for this purpose. With all the switches of the NS group in their 01T position, lamps WN, WS, WE and WW are extinguished and bars corresponding to lines 42 would be laid down across the exits EN and ES. In a similar manner he can eliminate east and west traiic, and again re-establish north and south traic by merely operating one knob 54 in one direction and the other in the opposite direction. Should he stop all traflc by throwing both knobs 54 into the off position, drawing them both toward him with one hand, he will not only stop all trame but through series circuit 49 illuminate the generally visible emergency signal 24 and sound the emergency horn 24. Had the trailic officer used four fingers to throw the switches N, S, E and W of both group EW and group NS to their volf positions, Aand had thereupon closed switch 50, lines of light 42 would be thrown completely around the crossing area, in addition to illuminating the visible emergency signal 24 and sounding the er'nergency horn 24. In any event, pedestrians seeing the emergency signal and hearing the horn should not cross and all traic within the crossing area should clear out.

The general rules of tralic applying in the sys-- tem so elaborated should be substantially as follows:

(a) Cars turning to the right must keep near the curb and may enter any open pocket.

(b) Cars turning to the left must enter either pockets exclusively devoted to the direction of the left turn or the mouth of an otherwise open pocket pertaining to any direction of traic. This simple rule minimizes occasion for blanketingl of the inside cars on left turns.

Islands 45, midway between curbing, and lines 42 combine with the outer circle of the turntable to define zones for pedestrian traflc. rSuch islands may likewise be used in connection with simple installations such as are indicated in Fig. 1 of my aforesaid patent, and as indicated generally in Fig. 5 of the accompanying drawings. To produce-this result, it is but necessary to add the apparatus of Figs. 2 to 5, and the island lamps 43 andthe zone lamps 39, similar to those used in Fig. 9 of my aforesaid patent, with appropriate circuits.

In Fig. 4 I show a continuation of the circuits system of my invention is interlocked with the system of the halt and go type, so that a number o f the crossing installations in times of extremely heavy traflic, such as may not be taken care of by the turntable, may be connected together and operated as one by the halt and go method. This is simply accomplished by interpolating relays 64, 65 controllable from a central lstation, CG, which relays remove` the local control of the signals 22, 23 and 24 and render the signals subject to distant control over the circuits 66', 67', so that a number of successive signals in a Agiven avenue of tramo may ybe controlled. together from a central pointat Will. It is this subject matter which .forms the basis of this divisional case.

Fig. 1 shows the apparatus 'which I have devised as a part of my invention for such'a central control station, 68 is a chronometer of any standard circuit closing or circuit controlling make.v

In this case it is illustrated as closing and opening from mains 154-159 at regular intervals periodically the circuit of the stepping relay 69 of the traiic signal timing device 70. This device comprises a fixed disc 71 graduated in minutes and fractions of minutes up to 8 (by way of illustration) Movable in planes parallel to this disc about concentric axes are four contact arms. One of these 72 is fixed to shaft 73 which carriesvratchet 74 actuated by pawl 75 of the stepping relay 69. At siarting, arm 72 rests against a stop 76, and it is moved step by step, the steps corresponding to fractions of minutes from this stop, clockwise when relay 69 is operated by the chronometer 68. Arm 77 is frictionally or otherwise engag':d with arm 72 or its shaft 73 to be adjustable manually with respect to arm 72 but when released arranged to be carried step oy step along with arm 72. Arms 78 and 79, however, are adjustable about xed support SOand frictionally associated with that support and each other so that while angularly adjustable they remain xed with respect to dial 7l and are not steppod around with arm 72.

Electrically connected with the several arms of the timing vdevice '70 is a signal controlling switch 81 comprising a switch arm 82 moving commonly over two sets of interspersed contacts, the one 83 commonly connected to signal circuit 66 and the other 84 commonly connected ,to signal circuit 67. Arm 82 is rotatable step by step clockwise by stepping relay 85, pawl 86 and ratchet 87. l'n the timing device 70 the stepping arm 72 carries insulated from its body a contact 88 connected by conductor 89 in the circuit of stepping relay 85. Arm.77 carries a similar contact 90 connected by conductor with a relay 101, the

function of which relay isto effect flashing of the signals during energizvation thereof through a connection of arm 82 of the signal controlling switch 81 by conductor 102 and its alternate contacts 103 to the main 154 through flashing commutator`105; and, during deenergization, to provide a current pah to the main 154 excluding said commutator, through said contacts 103 and conductor 104. Arm 78 carries a contact 106 insulated from its body and connected by conductor 107 with the contacts of the series 83. Arm

79 carries a contact 108 similar to-106 but connected in this case by conductor 109 with the series 84 of the signal controlling switch.

Arm 72 and contacts 88 in addition to controlling stepping magnet 85 control the release magnet 110 of the timing device 70. This release magnet simultaneously withdraws both the stepping p awl 75 and the holding pawl 76. A weight 112 may then draw both arms 72 and 77 back to normal position against stop 76. In this position projection 113 on arm 72 engages and opens contacts 114 through which each of magnets 85, 101 and 110 lock up overa circuit generally denominated 115.

- While Fig. 1 is diagrammatic in the showing of devices and circuits, in Fig. 2 I show by a transverse section how the arms 72, '77, 78 and 79 and their contacts may be associated together without interference and movement through substantially the 360 of the 'timing dial secured. All of the arms and contacts are mounted within a circular casing 116. Arm 72 is given the form of a knob and with arm 77, which it carries frictionally, is supported from an elongated bearing 117 in the `body of the casing proper at the back. Arms 78 and 79, however, are independently and frictionally supported ina bearing 118 formed by a ferrule carried in the central opening of the dial 71 itself. The arms communicate by concentric thimbles respectively with insulating discs 119 of similar form which discs support concentrically metal rings which in turn carry the respective contacts 88, 90, 106 and 108. These contacts may indeed be nger-like extensions from rings 120. The ends of the contacts are respectively shaped as indicated in Fig. 3 so that 90 and 88 may pass freely back and forth over the ends of 106 and 108. Connection is made with this group of contacts by brushes 121 vwhich bear respectively on rings 120, which areinsulated from each other, carried by a cross bar 76 in the central vertical plane of the axis, and which are respectively connected with the circuits 89, 100, 107 and 109. 'Ihe brushes are on the near side of bar 76 while the contacts of the group to which they pertain are on the far side. Thus any or all of the contacts may be rotated clock-V wise away from bar '16 through substantially 360 until they come into engagement with the several brushes 121. So bar 76 constitutes a stop such as illustrated diagrammatically in Fig. l, defining the normal position of arms 72 and 77. Contacts 114 are carried by casing 116 and. are opened by a pin stop 113 carried on that disc 119 associated with contact 88 and arm or knob '12.

Reverting again lto Fig. l, it will be seen that the chronometer 68 also drives a recording device 123 which may carry in the usual course a sheet of recording material on its face laid o into 12 divisions corresponding to the hours of the day as is usual in time recorders.

Within the twelve circumferential divisions into hours of the day, the record carries a plurality of annular divisions into minutes according to the number of minutes represented on the dial 70 with which it is associated. Thus from zero minutes at or near the center of the sheet there are serially arranged eight annular divisions in the illustration taken. Playing over the face of this record sheet are two recording pens 123', 124, the one connected by cord 125 with that disc 119 on which contact 108 is mounted and the other connected by cord 126 with that disc 119 upon which contact 106 is mounted. Pens 123', 124, being drawn Atoward zero position by suitable f springs, it will be seen that with proper dimensions of connections, the pens will be drawn clownwardly to those annular graduations indicative of the positionsv to which arms 78 and 79 are set. So set they will trace upon the record sheet throughout the day the settings which arms 78, 79 are given at Various times, making a complete record of the signal operations.

Conductors 66, 67 leading from the interspersed groups of contacts 83, 84 associated with the respective arms 78, 79, are extended through double pole switch A and double pole double throw switch B, both located at the control station of Fig. 1, unto the signal mains 66', 67 which extend to the local stations in parallel. The switch A serves merely to open the signal lines. The switch B serves not only to open them but, when thrown into the upper closed position, to connect them both to one side of the source of power, we will say the positive side. When the signal lines are disconnected at switch A, however, they may be independently and separately connected to the source of power by a single pole doublethrow switch A' which is normally open and arranged toconnect with the source of power back of the control station switch S.

In the local stations through which the control line 66', 67' pass, as diagrammatically shown in Fig. 4, these signal lines connect directly through a local control double pole switch C with the local cut-in and cut-out relays 64, 65 previously mentioned. The opposite sides of these relays connect with the common conductor 163 and by way of conductors 152 and 153 to main 159. Relay 64 carries a, bank of four contact pairs 127 normally opened as indicated but closed when the relay is energized to close the circuits of the several lamps of the signal 22 to the source of power in parallel to circuits 156 but independently of the local traic officers control switches EW and NS. Relay 65 carries a similarly arranged and operated group of contacts 128 to connect the lamps of signal 23 to the source of power. Connection to the source of power in each case is made by way of common conductor 129 which extends through the normally closed contact 130 of relay 131 to conductor 132 which can be traced to the source of power through a switch 133 associated with the switch 234, which is the main switch of the local station.

The circuit of relay 131 is jointly controlled by relays 64 and 65 through contacts 134 and 135 in such manner that relay 131 is energized when relays 64 and 65 are pulled up at the same time. In such case contact 130, through which the lamp circuits-of signals 22 and 23 are connected to the source of power, is opened and normally opened contact 136 is closed connecting signal 24 to the source `of power.

Normally connected between the signal line 66', 67 and common conductor 152 are three pilot lamps, the one ns indicating the operation of north and south trafc signals, another ew indicating the operation of east and west signals i and a third em indicating the operation of emergency signals. y

The system so organized may be used under either local or central station control at will. During the quieter hours of tramo each day the operation will be under local control. During certain rush hours, however, the connected series of stations will be operated under central control. Assuming operation to be proceeding under local control as heretofore outlined, and the rush hour to have arrived, the oicer at the central station in order to undertake control of the series of stations at his command proceeds as follows: First, he setsiarms '18, 79 and 'Z7 in accordance with the number of minutes he desires to allot, north and south, east and west and warning signals, at the particular. hour. In setting these arms, arm 72 is held by 'hand against the tcp 76 so that it may not be drawn frictionally out' of position when arm '17 is set. Next the motor which drives cornmutator 105 is started, though this motor may be connected directly across the mains andv started when power is put across the mains later. Thirdly, yswitches A and B opened during local control are closed to connect the signal lines 66', 67' to the signal control mechanisms. Fourthly, the switch S throwing on the power is closed.

Placing power on the mains places power by way of conductor 104, contact 103, conductor 102 on the arm 82 of the signal switch and through it on conductor 66 connecting with signal main 66. This lights' up pilot lamps ns in each of the several local stations and immediately apprises the oflicers at the local stations that the time for central control has arrived and that the central oilce is operating its control.v The local oflicer may or may not at the moment be ready to shift from local to central control due to local trailic conditions which he alone is in a position to observe, such for example as a traic jam in one direction or another or a certain congestion which must be relieved. But having observed the pilot signal, it then becomes his duty to so regulate the conditions at his crossing as` to, at the earliest possible moment, harmonize withV the control from the central station which from this time on is manifest upon the pilot lamps ns and ew. From this time on, as long as the central station continues its operation, these pilot lamps will indicate its functioning precisely, first the white lamp flashing, then the green lamp, etc. Having relieved any special traflic condition which may have existed by special manipulation of his local switches, the oicer having reference to the pilot signals then either operates his local switches in gang in -substantial synchronism with the central station signals on the pilot lamps until traic is adjusted approximately thereto or else opens all his local station switches including switch 234, and at the same time closes switch 133. He then closes switch C which until now has been open, thereby connecting relays 64 and 65 to the signal mains 66', 67', respectively. Then in addition to the pilot lamps, whenever power is placed upon either signal main, the corresponding signal` 22 or 23, as the case may be, is operated as a whole, each lamp in it being illumined. Thus at the time the pilot lamp ns is illumined, relay 64, which controls signal 22 governing north and south traffic, is energized. From this time on the local oicer is expected to retain all of his local switches in olf positions and to retain closed switches 133 and C having to do with the central station control.

Reverting now to the central station at which control has been inaugurated, as soon as switch S was closed, stepping magnet 69 started stepping arms 72 and 77 of the timing device toward arms 78 and 79. This stepping continues once each second or several seconds as may be desired, the arms being held in stepped'position by retaining pawl 76,until arm 72 reaches arm 79, the arm which indicates the time allotted for north and south trac. contacts and 88 have successively passed over contact 106 carried by arm 78 by which the time allotted to east and west traic is controlled. But this passage is of no eifect, since contact 106 is at the time disconnected from the source of power, arm 82 of the signal switch vbeing at the moment associated with the complemental group of contacts 84. The moment contact 90 of arm 77 reaches contact 108 of arm 79, power is applied thrcugh arm 82, contact 84, conductor 109, contacts 108 `and 90 and conductor 100 to the commutator relay 101. The resultant energization of relay 101 shifts the connection of signal switch arm 82 from direct connection with the source of power to indirect connection therewith through commutator 105. This shiftmay be made through make before break contacts if necessary or other equivalent device to insure the full pulling up of relay 101. Relay 101 having pulled up locks up by conductor` 115 through the now closed contacts 114 to the source of power Therefore, for the interval of time represented by the angle distended between arm 77 and the following arm 72, the north and south signals displayed at the various local stations, that is the signals 22, will be dashed in a characteristic manner instead of being displayed continuously. This is the indication to traic that In the meantime, however,

a signal is about change, an indication corresponding to the present amber lamp signals which are in common use for the same purpose.

When contact 88 of arm 72 reaches contact 108 after this change interval, power is applied by conductor 89 from contact 108 to stepping magnet 85- of the signal switch 81. This steps arm 82 off the group of contacts 84 and unto the group 83. This takes power off of the main 66', deenergizes all of the relays 64, energizes instead the relay 65, shifting from the north and south signals 22 to the east and west signals 23. This shift takes place the moment arm 82 is shifted. Arm 82 and the spacing of'contacts 83, 84 being properly proportioned, there need be`no overlapping of signals and no simultaneous energization of relays 64, 65 associated with the emergoncy signals. And the locking contacts of stepping relay 85 being adjusted with sullicient closeness, operating independently of the stepping operation if need be, the stepping is full, complete and exact for then the energization of relay 85 is not interrupted by the stepping of arm 82 through which it receives its initial power and which it in turn controls. There are many devices known to the art for adjusting such conditions and I contemplate using any of them which the situation may require. So, the tralc signals are set now for east and west traffic.

Relay 85 locks up over circuit 11-3 and through contacts 114 just as did commutator relay 101. When 88 and 108 contacted, however, in addition to closing the circuit of stepping magnet 85, they closed also the circuit through conductor to the release magnet 110 associated with the stepping pawl 75 and the holding pawl 76. This magnet, too, locks up over circuits 114, releasing4 both pawls. Instantly the weight 112 associated with the arms 72, 77 draws these arms back toward the stop 76. Contacts 88 and 90 in succession ratchet over contact 106 now connected to a source of power, but by reason of the inclination of the ends of contacts 90, 88 (see Fig. 3)

and the insulation of the undersides thereof, they do not effect electrical contact with contact 106 so that no circuit is closed thereby and the east and west signals 23 continue, to be displayed. Just before arm 72 reaches stop 76, pin 113 associated with contacts 114 engages the longer of these contacts and moves it away from the shorter, opening the locking circuits of all of the relays of the control mechanism. This gives the mechanism a fresh start, which it takes immediately, stepping magnet 69 and holding pawl 76 again cooperating. This time, when arm 77 reaches arm'78 controlling the Veast and west signal, the device having been stepped through the arc representative of the timel allotted to east and west traffic, contacts 90 and 106 place power on commutator relay 101 and the east and west signals are flashed indicating the change in the same manner as were the north and south signals 22. Immediately following the interval of change, contact 88 contacts with 106, power is placed on stepping relay 85 which this time steps the control arm 82 back to the group 84 which controls the north and south signals over line 66' and traflic is changed again to north and south trac.

At the same moment, release magnet 110 is again closed, the arms 72 and 77 are drawn back toward normal, without this time having stepped so far for not only does contact 90 ratchet pass on its reverse or insulated side, but also arm 106 has by this time been disconnected from the source of power through the stepping of arm 82.

Instead of operating the approach and exit line lights, AE, AW, etc., from the control switches direct, they may beoperated through relays, and in this connection in case of a display of the emergency signal stopping all traffic, there may be used a relay in parallel with`the emergency signal, which relay extinguishes all of thevapproach and exit line lights, or at least the outer ones of them, whenever the emergency signal is operated, whereby pedestrians are not led to cross the approaches by the normal appearance of the lines in disregard of the emergency signal.

As to modications of the circuits themselves, there are many which may be made without departing in any way from the generic spirit of the invention. 'I'here are, furthermore, many equivalents of detail which may be used.v The apparatus as described has not yet been constructed, and it is anticipated that when it is constructed there will be found use for a few at least of the scores of known equivalents and means for attaining the specified results in the realm of the electrical arts, particularly those arts pertaining to signalling and communication, such as the telephone and telegraph arts.

It is my belief that I have described the operations with suicient clarity to enable anyone skilled in the arts to achieve the results claimed,k

with or without the aforementioned equivalents and means which he has at his command.

All these and oth'er modications which fall within the purview of the generic spirit are intended to be covered by the annexed claims.

What I claim as new and useful and desire to protect by Letters Patent is:-

l. A traflic signalling system comprising a plurality of local trac control stations having routine traic signals, a central control station, means operated from said central station for controlling vsaid signals, means at each station for operating said signals manually at the local point, means at each local station for shifting control from the second named means to the central station control means, and pilot indicator means at each station connected to the central station for indicating the instantaneous signalling operating condition established by the central station operating means.

2. In a traic signalling system having two different indications, means for alternately displaying said indications for a period of time to indicate stop and go, and meansto intermittently display one of said indications at the end of its period to indicate caution,

3. A shaft, a time controlled driving means adapted to rotate said shaft in one direction, means to engage and disengage said shaft to and from said driving means, but normally acting in engaging position, means to return said shaft to a predetermined position when disengaged from said driving means, a stationary index mounted with its reference point at said predetermined position, a-pair of stationary contacts, means for mounting said contacts about said shaft in various fixed positions which can be determined from said index, a cooperating contact, means for mounting last said contact on said shaft for rotation therewith, in a position to come to said reference point when said shaft returns to its predetermined position, and adapted to engage the first said contacts when the shaft is rotated.

4. In a device as in claim 3, another contact,

and means to adjustably mount said last namedk contact on said shaft for rotation therewith and in advance of the said co-operating contact.

5. In combination with the device of claim 3, a pair of conductors, means for selectively energizing said conductors, alternately operable upon engagement of Asaid co-operating contact with one of said stationary contacts to energize one of said conductors and upon engagement of said co-operating contact with the other ofsaid sta.-- tionary contacts to energize the other of said conductors.

6. In combination with the device of; claim 3, means to momentarily operate said disengaging means upon alternate engagement of the said cooperating contact with said pair of stationary contacts.

'7. In combination with the device of claim 3, a pair of conductors, means for selectively energizing said conductors, alternately operable upon engagement of said cooperating contact with one of said stationary contacts to energize one of saidconductors and upon engagement of said cooperating contact with the other of said stationary contacts to energize the other of said conductors, together with means to momentarily operate said disengaging means upon alternate engagement of the said cooperating contact with said pair of stationary contacts.

8. In a traffic control system comprising a control station, traic stations at a plurality of local points and each comprising-signals for governf ing traic movements, means for eifecting display of its associated signals pursuant to a progressive routine initiated responsive to said control station, means for local manual operation to control said displays, means for transferring control of said displays from said second named means to said first named means, and means at each local station effective during manual con" trol for indicating the progression of the routine of displays established at other local stations responsive to initiation of said control station.

9. In a traffic control system comprising a control station, traiic stations at a plurality of local points and each comprising-signals for governlng trailic movements, means for effecting display of its associated signals pursuant to a progressive routine initiated responsive to said control station, means for local manual operation to control said displays, means for transferring control of said displays from said second named means to said rst named means, and means at each local station independent of said traic signals for continuously indicating the progression of the routine as initiated by said control station.

10. In a trailc control system comprising a control station, traflic stations at a plurality of local points and each comprising-signals for governing traffic movements, means for effecting display of its associated signals pursuant to a progressive routineinitiated responsive to said control station, means for localmanual operation to control said displays, means for transferring control of said displays from said second named means to said first named means, and means at each local station for indicating the progression of the routine as initiated by said control station.

l1. In a traic signalling system having two dierent indications, means for effecting the display of a "go indication for certain traffic during a "stop indication for other traflic, and means for4 alternately effecting stop indications for said first named and for said other trafc for predetermined intervals, and means to intermittently display one of said indications during a vpredetermined portion of one of said intervals.

12. In a traiiic signalling system having two different indications, means for alternately displaying'said indications for periods of time for respectively indicating "stop and go, and

means to intermittently display one of saidin-4 dications in a predetermined portion of one of said periods to indicate caution.

13. In a traiiic signalling system having two different indications, means for alternately effecting display of said indications for periods of time respectively indicating stop and go, and means to intermittently display one of said indications during the latter portion of one of .said

periods. l

14. In a traiiic signalling system having two different indications, means for alternately effecting continuous displays of said indications for periods of time to indicate stop and go, and means to intermittently display one of said indications during oneof said periods.

JOHN P. TARBOX. 

